1. Field of the Invention
The present invention relates broadly to portable bridges, and more particularly to portable bridges suitable for military purposes, employed for crossing wet and dry gaps. More specifically, the instant invention relates to a modular lightweight bridge assembly which is portable and will support lightweight vehicles such as small trucks, jeeps and the like, as well as serving as a foot bridge.
2. Background of the Invention
For military purposes, and perhaps for civilian use in remote areas and emergency situations, there is a need for a lightweight, manually deployable bridge which can be towed by lightweight vehicles such as those used with light military forces. Specifically for military deployment, there is a need for a bridge which requires no auxiliary power system for its launch and recovery, and which may be deployed either by the towing vehicle or manually by ordinary troops with minimal training. One difficulty which needs to be addressed with available bridges is that the bridges have both high profile and audible signatures, which makes the bridges easy to identify as targets.
3. Prior Patent Literature
The patent literature includes a number of examples of bridges carried by vehicles. However, in most cases, the bridges are heavy structures for supporting trucks, tanks and the like and are not towable by lightweight vehicles, nor are they manually deployable with ease. Exemplary of such bridges are the bridges disclosed in U.S. Pat. Nos. 4,635,311; 4,319,375; 2,556,175; 2,687,225; and 3,105,251.
The patent literature also includes relatively lightweight structures such as those disclosed of U.S. Pat. Nos. 2,704,989; 2,977,612; and 4,521,932. The bridge disclosed in U.S. Pat. Nos. 2,704,989 is a floating bridge exemplified in one embodiment by an omnibus structure which can also serve, among other things, as an assault vehicle, ambulance and troop carrier. U.S. Pat. No. 2,977,612 discloses a portable floating bridge which is made up of modular sections of rather robust construction, not necessarily suitable for manual deployment nor towing by light vehicles. U.S. Pat. No. 4,521,932 discloses a bridge in which lightweight construction is employed, but the bridge still needs a special, rather large vehicle, including a derrick for achieving erection.
Clearly, prior art bridge devices do not fill the need for a low-profile, lightweight, collapsible modular bridge which may be transported by a light vehicle, such as a light infantry jeep. None of the bridges disclosed in the aforementioned prior art patents can be conveniently parachuted from an airplane or conveniently delivered by helicopter.